The invention relates to a method for producing a field effect transistor on a substrate comprising a support layer, a sacrificial layer and a semi-conducting layer. The method comprises forming an active area in the semi-conducting layer, the active area being delineated by a closed peripheral insulation pattern and comprising an additional pattern made from insulating material, etching the insulating material of the additional pattern to access the sacrificial layer, etching the sacrificial layer resulting in formation of a first cavity, forming a dielectric layer on a top wall of the first cavity, and depositing an electrically conducting layer in the first cavity.
The invention also relates to a semiconductor device comprising a plurality of transistors on a substrate, each transistor being formed on one active area and associated with one ground plane.